Female reproductive senescence is marked by the progressive loss of ovarian function, menstrual regularity[unreadable] and endocrine homeostasis. Reproductive aging is accompanied by vasomotor and urogenital symptoms[unreadable] preceding the event of menopause itself, and can contribute to pathophysiological syndromes including[unreadable] osteoporosis and cardiovascular disease. Population and genetic studies of nonhuman primates will[unreadable] enhance how we understand perimenopause - the menopausal transition. Female baboons of SFBR in[unreadable] particular offer a unique model to understand human reproductive aging because we can accurately[unreadable] determine their life-long menstrual behavior from perineum turgescence and, like humans, are non-seasonal[unreadable] breeders. This Project will study individual menstrual dynamics to quantify the state of reproductive senescence[unreadable] for all females of the large study population, and it will generate detailed profiles of daily individual multi-cycle[unreadable] gonadotropic and steroid hormones. These measures will provide individual based estimates on a[unreadable] population scale to estimate the contribution of environment, maternal and genetic components to variation[unreadable] reproductive aging, and to identify genetic loci that influence reproductive patterns and perimenopause. The[unreadable] data will provide unique opportunities to evaluate mechanistic models for perimenopause. Coupled with the[unreadable] program-wide multidimensional measures of somatic aging, we shall evaluate the extent that reproductive[unreadable] and somatic aging are concordant or independent.